AuthorTopic: Do I change the Viscous Coupling or Transfer Box?  (Read 1272 times)

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Offline Dr Strangeglove

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Do I change the Viscous Coupling or Transfer Box?
« on: April 17, 2007, 14:11:07 »
I think my viscous coupling has gone on my 3.9 EFi (1991).  I need to know a definite test to make sure that the one on it is duff before I go taking it off so can anyone tell me for definite how to check?

I have already purchased a transfer box and coupling from ebay.  It has the hand break cable etc. attached.  Do I change the full unit or shall I just change the viscous unit.

Thanks

Mick
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Offline pongo_bob

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Do I change the Viscous Coupling or Transfer Box?
« Reply #1 on: April 17, 2007, 22:55:08 »
I'm sure mine is seized. I'm on 110K miles. I jacked up the front two wheels , put a large screwdriver through the front propshaft UJ and it moves slowly about 1/16 of a turn either way using all the force I can muster. The steering feels heavy and it doesn't seem to coast at all.

I bought a VC from http://www.legs.co.uk/ . The only difference between theirs and LR is £600 and the box it comes in :shock:

Because I don't have  a hoist or a pit I keep putting this job off. If anyone has got any tips I'm all ears.
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Offline Skibum346

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Do I change the Viscous Coupling or Transfer Box?
« Reply #2 on: April 17, 2007, 23:42:29 »
Typical symptom is scrabbling on full lock at slow speed from front wheels think there is also a test involving jacking the front but not sure.

I'd change the whole lot. if the VC has siezed then it'll be a fair bet the chain and various other components will need to be looked at as well soon so your just putting off the inevitable.

Change it and refurb it... stick it in the garage on the spares shelf for next time!

Good luck

Skibum

Offline Dr Strangeglove

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Do I change the Viscous Coupling or Transfer Box?
« Reply #3 on: April 18, 2007, 08:06:49 »
I will attempt the whole unit then.  I will need to fit a new breather pipe and I think I will also have a look at the hand-break before I put it on.  Is it worth doing anything else to it whilst it is off the vehicle?

It has the hand break cable on it which seems in decent condition, I presume it is better to leave that on and connect that to the hand-break!

Any tips please let me know.
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Offline Skibum346

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Do I change the Viscous Coupling or Transfer Box?
« Reply #4 on: April 18, 2007, 11:39:05 »
Not sure if it affects your vehicle but I remember hearing something about some gearboxes do not have a cross drilled output shaft leading to drying and accelerated wear.

Good chance to check the state of it though if it's in need of TLC I'd suspect it's a change the gearbox job.

Skibum

Offline Jonny Boaterboy

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Do I change the Viscous Coupling or Transfer Box?
« Reply #5 on: April 18, 2007, 19:53:42 »
My viscus went as well, there is a test you can do which Im sure someone will come up with soon, but if its not coasting round tight bends and and you can here the wheels chaffing especially when there is gravel or grit on the road then thats a good sigh that the viscus has seized. I think the test is to jack up one wheel and see if you can turn it, if you can the viscus is working, if not its seized.

I changed mine myself and its a fairly straight forward job and have not had any other problems since. I would go with just changing the cuppling as it will be less work

good luck mate!

Jonny

Offline Range Rover Blues

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Do I change the Viscous Coupling or Transfer Box?
« Reply #6 on: April 18, 2007, 20:23:51 »
The coupling can be swapped without removing the whole box IIRC, the front housing comes away (you loose all the oil) and in it is the Viscous unit.

The oil in the viscous is sealed in, so unless there are any horroras inside the tranfer box then there is no reaosn to suspect it's any worse than a second hand unit, after all if it's second hand the car is came from wasn't worth keeping on the road, right :wink:

Here's a few ways of checking.

With the handbrake on and the car in neutral, jack up one front wheel.

With mine I can:

Just about undo the propshaft UJ against the stiffness of the Viscous unit, if I push quick the nuts come undone, if I push slow the propshaft turns.

Undo a wheel nut, agai if you push quick the viscous fluid does it's job and locks up, if I lean on the wheel wrench it turns, very, very slowly. That's all you need to happen.

I have heard about Visocu units locking up, it's caused by the Thermo-vicous fluid inside overheateing and turning to a hard rubber like substance that jams the fins within the unit, but I've never seen one, even in all the cars we used to break at my mate's place.

Any one need a transfer box, I have too many spare units here but they do hold their money, I've seen just the Viscous unit go for £150 on flea-bay :o
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Offline Dr Strangeglove

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Do I change the Viscous Coupling or Transfer Box?
« Reply #7 on: April 20, 2007, 17:47:12 »
I have been lucky - I got the full unit for £19.  The guy was working on a light weight with a RR chassis and had another two LR's outside.

He was a really nice guy and certainly knew what he was doing - a fantastic set-up and a restored 3l Capri under a dust cover in the corner! =P~
Too many sins, not enough temptation!
Too many armpits, not enough deodorant!
Forget maths, forget geometry
You cause explosions by being good at Chemistry
Too many mountains, not enough volcanoes!
Too many lawyers, not enough justice!!!

 






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